Arsenic Trioxide as a Radiation Sensitizer for 131I-Metaiodobenzylguanidine Therapy: Results of a Phase II Study

A therapeutic strategy integrating ultrasound-guided microwave ablation with nanocomposite hydrogels to enhance autophagy and suppress tumor growth in hepatocellular carcinoma

Microwave ablation (MWA) is widely recognized as an effective radical therapy for hepatocellular carcinoma (HCC). However, local ablation often results in a high risk of tumor recurrence. To address this challenge, we developed an effective anticancer drug delivery system comprising arsenic trioxide (As2O3)-loaded polyethylene glycol-dipalmitoylphosphatidylethanolamine (mPEG-DPPE) calcium phosphate nanoparticles (As2O3NPs) encapsulated within an injectable thermoresponsive hydrogel (ANPs-Gel). This study evaluated the therapeutic efficacy of MWA combined with ANPs-Gel in a rabbit hepatic VX2 tumor model. Ultrasound (US) and contrast-enhanced ultrasound (CEUS) were employed to assess tumor response and angiogenesis following treatment. The results demonstrated that MWA combined with ANPs-Gel significantly enhanced antitumor efficacy compared to other treatments, effectively inhibiting tumor growth and angiogenesis. Mechanistically, the therapeutic effects were associated with autophagy induced by MWA+ANPs-Gel, which played a critical role in promoting tumor cell death and suppressing epithelial-mesenchymal transition (EMT) both in vitro and in vivo. In vivo experiments further highlighted that the injectable thermoresponsive hydrogel system not only prolonged drug retention at the tumor site but also enhanced therapeutic efficacy by reducing EMT and preventing tumor recurrence. These findings suggest that MWA combined with ANPs-Gel provides a promising strategy for improving treatment outcomes in HCC through ultrasound-guided chemotherapy and targeted autophagy modulation. STATEMENT OF SIGNIFICANCE: This study introduces a potent therapeutic strategy that integrates ultrasound-guided microwave ablation (MWA) with a nanocomposite hydrogel to enhance autophagy and suppress tumor growth in hepatocellular carcinoma, as demonstrated in the rabbit VX2 hepatic tumor model. By combining advanced ultrasound guidance with a sophisticated nanomaterial platform, this approach significantly improves the efficacy of localized cancer therapy. Unlike conventional treatments, it not only ablates tumor cells but also regulates key cellular processes, such as autophagy, to amplify therapeutic outcomes. This work repurposes arsenic trioxide (Arsenic Trioxide) within a nanocomposite hydrogel delivery system and provides a detailed exploration of its therapeutic mechanisms when combined with MWA therapy. These findings pave the way for advanced clinical strategies in liver cancer management.

131I-mIBG therapy in relapsed/refractory neuroblastoma: A weapon from the future past

Neuroblastoma (NB) is the most common extracranial solid tumor in children, with variable outcomes ranging from spontaneous remission to high-risk cases often leading to relapse or refractory disease. Approximately 50 % of patients with NB have high-risk features, often experiencing relapse or refractory disease despite intensive treatments and the prognosis remains poor, with long-term event-free survival (EFS) rates below 10 %,Radioactive iodine-labeled meta-iodobenzylguanidine (¹³¹I-mIBG) therapy, leveraging NB cells' radiosensitivity and expression of the norepinephrine transporter (NET), has shown promise in treating relapsed or refractory NB. Since 1985, ¹³¹I-mIBG has been studied to determine the maximum tolerated dose and side effects, with recent trials exploring its use in front-line treatment. Our systematic review, based on MEDLINE, EMBASE, and Cochrane CENTRAL databases up to December 2023, evaluates the effectiveness and toxicity of ¹³¹I-mIBG therapy in relapsed/refractory NB. It also discusses its potential role in conjunction with emerging therapies like CAR-T cells, haploidentical stem cell transplantation, and dinutuximab beta.

Arsenic trioxide induces ferroptosis in neuroblastoma by mediating GPX4 transcriptional inhibition

Neuroblastoma (NB), the most common extracranial solid tumor in childhood, significantly contributes to cancer-related mortality, presenting a dearth of efficacious treatment strategies. Previously, our studies have substantiated the potent cytotoxicity of arsenic trioxide (ATO) against NB cells, however, the specific underlying mechanism remains elusive. Here, we first identified ATO as a novel GPX4 inhibitor, which could trigger the ferroptosis in NB cells. In vitro, ATO significantly inhibited the proliferation and migration ability of NB cells SK-N-AS and SH-SY5Y, and induced ferroptosis. Furthermore, the iron chelator deferoxamine reversed ATO-mediated intracellular reactive oxygen species accumulation and hindered the generation of the lipid peroxidation product malondialdehyde. Conversely, ferric ammonium citrate notably intensified its cytotoxic effects, especially on retinoic acid (RA)-resistant SK-N-AS cells. Subsequently, the quantitative real-time polymerase chain reaction results showed ATO significantly inhibited the transcription of GPX4 in NB cells. Remarkably, immunoblotting analysis revealed that MG132 exhibited a notable effect on elevating GPX4 levels in NB cells. Nevertheless, pretreatment with MG132 failed to reverse the ATO-mediated decrease in GPX4 levels. These findings suggested that ATO reduced the GPX4 expression level in NB cells by mediating GPX4 transcriptional repression rather than facilitating ubiquitinated degradation. In conclusion, our research has successfully indicated that ATO could induce ferroptosis and initiate lipid peroxidation by regulating the transcriptional repression of GPX4, and ATO holds promise as a potential anti-tumor agent in NB, specifically for patients with RA-resistant HR-NB.

Targeting GLI1 Transcription Factor for Restoring Iodine Avidity with Redifferentiation in Radioactive-Iodine Refractory Thyroid Cancers

Radioactive-iodine (RAI) therapy is the mainstay for patients with recurrent and metastatic thyroid cancer. However, many patients exhibit dedifferentiation characteristics along with lack of sodium iodide symporter (NIS) functionality, low expression of thyroid-specific proteins, and poor RAI uptake, leading to poor prognosis. Previous studies have demonstrated the effect of GLI family zinc finger 1 (GLI1) inhibition on tumor growth and apoptosis. In this study, we investigated the role of GLI1 in the context of redifferentiation and improvement in the efficacy of RAI therapy for thyroid cancer. We evaluated GLI1 expression in several thyroid cancer cell lines and selected TPC-1 and SW1736 cell lines showing the high expression of GLI. We performed GLI1 knockdown and evaluated the changes of thyroid-specific proteins expression, RAI uptake and I-131-mediated cytotoxicity. The effect of GANT61 (GLI1 inhibitor) on endogenous NIS expression was also assessed. Endogenous NIS expression upregulated by inhibiting GLI1, in addition, increased expression level in plasma membrane. Also, GLI1 knockdown increased expression of thyroid-specific proteins. Restoration of thyroid-specific proteins increased RAI uptake and I-131-mediated cytotoxic effect. Treatment with GANT61 also increased expression of endogenous NIS. Targeting GLI1 can be a potential strategy with redifferentiation for restoring RAI avidity in dedifferentiated thyroid cancers.

The efficacy and safety of Iodine-131-metaiodobenzylguanidine therapy in patients with neuroblastoma: a meta-analysis

Objective

Neuroblastoma is a common extracranial solid tumor of childhood. Recently, multiple treatments have been practiced including Iodine-131-metaiodobenzylguanidine radiation (¹³¹I-MIBG) therapy. However, the outcomes of efficacy and safety vary greatly among different studies. The aim of this meta-analysis is to evaluate the efficacy and safety of ¹³¹I-MIBG in the treatment of neuroblastoma and to provide evidence and hints for clinical decision-making.

Methods

Medline, EMBASE database and the Cochrane Library were searched for relevant studies. Eligible studies utilizing ¹³¹I-MIBG in the treatment of neuroblastoma were included. The pooled outcomes (response rates, adverse events rates, survival rates) were calculated using either a random-effects model or a fixed-effects model considering of the heterogeneity.

Results

A total of 26 clinical trials including 883 patients were analyzed. The pooled rates of objective response, stable disease, progressive disease, and minor response of ¹³¹I-MIBG monotherapy were 39%, 31%, 22% and 15%, respectively. The pooled objective response rate of ¹³¹I-MIBG in combination with other therapies was 28%. The pooled 1-year survival and 5-year survival rates were 64% and 32%. The pooled occurrence rates of thrombocytopenia and neutropenia in MIBG monotherapy studies were 53% and 58%. In the studies of ¹³¹I-MIBG combined with other therapies, the pooled occurrence rates of thrombocytopenia and neutropenia were 79% and 78%.

Conclusion

¹³¹I-MIBG treatment alone or in combination of other therapies is effective on clinical outcomes in the treatment of neuroblastoma, individualized ¹³¹I-MIBG is recommended on a clinical basis.

Arsenic trioxide in pediatric cancer - a case series and review of literature

Arsenic trioxide (ATO) has become an established component of treatment protocols for acute promyelocytic leukemia (APL) with excellent efficacy and no relevant sustained toxicity. Part of its action has been attributed to the inhibition of Hedgehog signaling (Hh) which enables a possible therapeutic approach as many pediatric tumor entities have been associated with increased Hh activity. We retrospectively analyzed 31 patients with refractory and relapsed pediatric cancer who were treated with ATO at the University Children's Hospital of Tuebingen. Additionally a literature review on the clinical and preclinical use of ATO in pediatric cancer treatment was performed.ATO alone as well as combinations with other drugs have proven effective in vitro and in mouse models of various pediatric malignancies. However, only few data on the clinical use of ATO in pediatric patients besides APL exist. In our patient sample, ATO was overall well tolerated in the treatment of various pediatric cancers, even in combination with other cytostatic drugs. Due to distinct tumor entities, differently progressed disease stages and varying co-medication, no clear statement can be made regarding the efficacy of ATO treatment. However, patients with proven Hh activation in molecular tumor profiling surpassed all other patients, who received ATO in an experimental treatment setting, in terms of survival. As molecular profiling of tumors increases and enhanced Hh activity can be detected at an early stage, ATO might expand its clinical use to other pediatric malignancies beyond APL depending on further clinical studies.

The ATO/miRNA-885-5p/MTPN axis induces reversal of drug-resistance in cholangiocarcinoma

PURPOSE

Cholangiocarcinoma (CCA) is the second most malignant tumor of the hepatobiliary system. Due to its cumbersome early diagnosis and rapid progression, chemotherapy has become the main treatment option. Primary drug resistance is a major cause of the poor efficacy of chemotherapeutic drugs. Therefore, it is considered urgent to explore new drugs to overcome primary drug resistance of CCA.

METHODS

Western blot and qRT-PCR assays were used to assess the expression of myotrophin (MTPN) and microRNA-885-5p (miR-885-5p) in CCA tissues and cells. The viability of CCA cells treated with arsenic trioxide (ATO), 5-fluorouracil (5-Fu) and cisplatin (CDDP) was analyzed using a CCK-8 assay. A luciferase reporter assay was used to assess the interaction between miR-885-5p and MTPN. Kaplan-Meier analyses were used for survival assessments.

RESULT

We found that ATO can reduce the resistance of CCA cells to 5-Fu and CDDP and promote the killing effect of 5-Fu and CDDP. Low-dose ATO showed an anti-drug-resistance effect through up-regulation of the expression of miR-885-5p. Combined with sequencing results and database predictions, we found that MTPN may serve as a direct target of miR-885-5p. After MTPN knockdown, the sensitivity of CCA cells to 5-FU and CDDP was increased. Finally, we found that ATO can reverse chemotherapy resistance induced by overexpression of MTPN.

CONCLUSION

Our data indicate that the ATO/miR-885-5p/MTPN axis may serve as a target for improving the sensitivity of CCA cells to chemotherapy.

Radiopharmaceutical therapy in cancer: clinical advances and challenges

Radiopharmaceutical therapy (RPT) is emerging as a safe and effective targeted approach to treating many types of cancer. In RPT, radiation is systemically or locally delivered using pharmaceuticals that either bind preferentially to cancer cells or accumulate by physiological mechanisms. Almost all radionuclides used in RPT emit photons that can be imaged, enabling non-invasive visualization of the biodistribution of the therapeutic agent. Compared with almost all other systemic cancer treatment options, RPT has shown efficacy with minimal toxicity. With the recent FDA approval of several RPT agents, the remarkable potential of this treatment is now being recognized. This Review covers the fundamental properties, clinical development and associated challenges of RPT.

Targeted Radionuclide Therapy for Patients with Metastatic Pheochromocytoma and Paraganglioma: From Low-Specific-Activity to High-Specific-Activity Iodine-131 Metaiodobenzylguanidine

Low-specific-activity iodine-131–radiolabeled metaiodobenzylguanidine (I-131-MIBG) was introduced last century as a potential systemic therapy for patients with malignant pheochromocytomas and paragangliomas. Collective information derived from mainly retrospective studies has suggested that 30–40% of patients with these tumors benefit from this treatment. A low index of radioactivity, lack of therapeutic standardization, and toxicity associated with intermediate to high activities (absorbed radiation doses) has prevented the implementation of I-131-MIBG’s in clinical practice. High-specific-activity, carrier-free I-131-MIBG has been developed over the past two decades as a novel therapy for patients with metastatic pheochromocytomas and paragangliomas that express the norepinephrine transporter. This drug allows for a high level of radioactivity, and as yet is not associated with cardiovascular toxicity. In a pivotal phase two clinical trial, more than 90% of patients achieved partial responses and disease stabilization with the improvement of hypertension. Furthermore, many patients exhibited long-term persistent antineoplastic effects. Currently, the high-specific-activity I-131-MIBG is the only approved therapy in the US for patients with metastatic pheochromocytomas and paragangliomas. This review will discuss the historical development of high-specific-activity I-131-MIBG, its benefits and adverse events, and future directions for clinical practice applicability and trial development.

Current Consensus on I-131 MIBG Therapy

Metaiodobenzylguanidine (MIBG) is structurally similar to the neurotransmitter norepinephrine and specifically targets neuroendocrine cells including some neuroendocrine tumors. Iodine-131 (I-131)-labeled MIBG (I-131 MIBG) therapy for neuroendocrine tumors has been performed for more than a quarter-century. The indications of I-131 MIBG therapy include treatment-resistant neuroblastoma (NB), unresectable or metastatic pheochromocytoma (PC) and paraganglioma (PG), unresectable or metastatic carcinoid tumors, and unresectable or metastatic medullary thyroid cancer (MTC). I-131 MIBG therapy is one of the considerable effective treatments in patients with advanced NB, PC, and PG. On the other hand, I-131 MIBG therapy is an alternative method after more effective novel therapies are used such as radiolabeled somatostatin analogs and tyrosine kinase inhibitors in patients with advanced carcinoid tumors and MTC. No-carrier-aided (NCA) I-131 MIBG has more favorable potential compared to the conventional I-131 MIBG. Astatine-211-labeled meta-astatobenzylguanidine (At-211 MABG) has massive potential in patients with neuroendocrine tumors. Further studies about the therapeutic protocols of I-131 MIBG including NCA I-131 MIBG in the clinical setting and At-211 MABG in both the preclinical and clinical settings are needed.

Assessment of Organ Dosimetry for Planning Repeat Treatments of High-Dose 131I-MIBG Therapy: 123I-MIBG Versus Posttherapy 131I-MIBG Imaging

PURPOSE

To evaluate detailed organ-based radiation-absorbed dose for planning double high-dose treatment with I-MIBG.

METHODS

In a prospective study, 33 patients with high-risk refractory or recurrent neuroblastoma were treated with high-dose I-MIBG. Organ dosimetry was estimated from the first I-MIBG posttherapy imaging and from subsequent I-MIBG imaging prior to the planned second administration. Three serial whole-body scans were performed per patient 2 to 6 days after I-MIBG therapy (666 MBq/kg or 18 mCi/kg) and approximately 0.5, 24, and 48 hours after the diagnostic I-MIBG dose (370 MBq/kg or 10 mCi/1.73 m). Organ radiation doses were calculated using OLINDA. I-MIBG scan dosimetry estimations were used to predict doses for the second I-MIBG therapy and compared with I-MIBG posttherapy estimates.

RESULTS

Mean ± SD whole-body doses from I-MIBG and I-MIBG scans were 0.162 ± 112 and 0.141 ± 0.068 mGy/MBq, respectively. I-MIBG and I-MIBG organ doses were variable-generally higher for I-MIBG-projected doses than those projected using posttherapy I-MIBG scans. Mean ± SD doses to liver, heart wall, and lungs were 0.487 ± 0.28, 0.225 ± 0.20, and 0.40 ± 0.26, respectively, for I-MIBG and 0.885 ± 0.56, 0.618 ± 0.37, and 0.458 ± 0.56, respectively, for I-MIBG. Mean ratio of I-MIBG to I-MIBG estimated radiation dose was 1.81 ± 1.95 for the liver, 2.75 ± 1.84 for the heart, and 1.13 ± 0.93 for the lungs. No unexpected toxicities were noted based on I-MIBG-projected doses and cumulative dose limits of 30, 20, and 15 Gy to liver, kidneys, and lungs, respectively.

CONCLUSIONS

For repeat I-MIBG treatment planning, both I-MIBG and I-MIBG imaging yielded variable organ doses. However, I-MIBG-based dosimetry yielded a more conservative estimate of maximum allowable activity and would be suitable for planning and limiting organ toxicity with repeat high-dose therapies.

Norepinephrine Transporter as a Target for Imaging and Therapy

The norepinephrine transporter (NET) is essential for norepinephrine uptake at the synaptic terminals and adrenal chromaffin cells. In neuroendocrine tumors, NET can be targeted for imaging as well as therapy. One of the most widely used theranostic agents targeting NET is metaiodobenzylguanidine (MIBG), a guanethidine analog of norepinephrine. ¹²³I/¹³¹I-MIBG theranostics have been applied in the clinical evaluation and management of neuroendocrine tumors, especially in neuroblastoma, paraganglioma, and pheochromocytoma. ¹²³I-MIBG imaging is a mainstay in the evaluation of neuroblastoma, and ¹³¹I-MIBG has been used for the treatment of relapsed high-risk neuroblastoma for several years, however, the outcome remains suboptimal. ¹³¹I-MIBG has essentially been only palliative in paraganglioma/pheochromocytoma patients. Various techniques of improving therapeutic outcomes, such as dosimetric estimations, high-dose therapies, multiple fractionated administration and combination therapy with radiation sensitizers, chemotherapy, and other radionuclide therapies, are being evaluated. PET tracers targeting NET appear promising and may be more convenient options for the imaging and assessment after treatment. Here, we present an overview of NET as a target for theranostics; review its current role in some neuroendocrine tumors, such as neuroblastoma, paraganglioma/pheochromocytoma, and carcinoids; and discuss approaches to improving targeting and theranostic outcomes.